SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '9d71920e13f9c91a56ffd8f1e3b2da30c901f75591131a58ff3cab543c657b76' 
  AND token = 'fAXRtJV1pljL7k5w9WE3i6imHKZJQYMDXmOAKsx1bCM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}